Do electric vehicles need gears...

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BarelyAWake

BarelyAWake

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Jul 21, 2009
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Food for thought... research it yourself, these are just the first few search returns as examples;



Greenoptimistic Are electric vehicle transmissions necessary?: http://www.greenoptimistic.com/electric-cars-gears/

Wiki Performance acceleration and drivetrain design: https://en.wikipedia.org/wiki/Electric_car#Acceleration_and_drivetrain_design

AskEngineers: Why don't electric cars use transmissions?: https://www.reddit.com/r/AskEngineers/comments/1wymlw/why_dont_electric_cars_use_transmissions/

Quora Why does a gear system make sense only for combustion engines?: http://www.quora.com/Why-do-Tesla-c...system-make-sense-only-for-combustion-engines
 
cannonball2

cannonball2

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Oct 28, 2010
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Colonial Coast USA.
Among the many negative traits associated with EVs when compared to their ICE powered counterparts(range, expense, increased weight, etc.) the lack of need of a formal transmission and its complexity has always been a big plus.
I found it interesting that the torque drops with rpm and I guess its a component of the typical unloading of a vehicle as it hits its cruise speed sweet spot. I have seen watching a wattmeter that my bike is actually more efficient at certain higher speeds than easing along slowly.
It does seem unless the Emotor is a direct drive that a form of gear reduction/gearbox is necessary(even my Ezgo has such). So in fact most larger EVs do have a transmission its just not shiftable/variable but fixed.
My little geared motors have a planetary transmission.
 
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BarelyAWake

BarelyAWake

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I agree cannonball many have gear reduction/redrives, it's the lack of shifting, multiple speed transmissions no matter the application vs the ongoing trends in ebike marketing I find interesting. There's some advantages to a mid-drive but shifting really isn't one of them, particularly given the most common application is with the 7sp & up derailleur systems, already prone to maintenance demands it seems an unnecessary additional complication. Likely one of the most demanding applications would be Pikes Peak, where single speed EVs now dominate http://electricracingnews.com/pikespeak.html
There's been some talk of concessions made in an attempt to appease the ICE crowd, styling that infers a more traditional "engine" may be lurking under the covers, even electronic vroomie noises... If you've seen the latest Avengers movie, the sound effects added to the Harley-Davidson Livewire EV are a laugh riot, particularly the "shifting" of a single speed drive train lol: http://www.motorcyclenews.com/news/...livewire-in-new-avengers-age-of-ultron-movie/
The Harley rep admits there's artificial sound generation in the actual prototype as well: http://www.autoblog.com/2014/08/11/jay-leno-harley-davidson-livewire-electric-motorcycle-video/
 
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cannonball2

cannonball2

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Oct 28, 2010
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I agree on the reductions not being a traditional transmission. At least with Ebikes there is an alternative with the DD hub motors, which could open a discussion on efficiency. I don't know if there are direct drive wheel motor EVs out there as I don't keep up much with such. But it would seem that would be the most efficient and would easily allow 4+ wheel drive as long as there is a good means of throttle application between the multiple motors.

The racing you speak of reminds me of the flap that occurred when the Mazda/Wankel engines first showed up in racing and thoroughly battered their displacement classes. Soon they were placed in with the bigger classes. I always felt that wrong as it squashes innovation. Left where they were placed would have probably brought more advances in engine development from their direct competition.

I hope that doesn't happen with E racing. If it dominates ICE too bad. Fake sounds! Ridiculous! The sounds of the racing E motorcycles winding out have a beauty of their own. This is the 21 century after all.
 
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